feat: add Usage Limits Panel component with usage tracking and visual indicators for limits

style: implement custom color schemes and gradients for account section, enhancing visual hierarchy

backend/igny8_core/auth/views.py

@@ -529,6 +529,14 @@ class SiteViewSet(AccountModelViewSet):
             if user and user.is_authenticated:
                 account = getattr(user, 'account', None)
         
+        # Check hard limit for sites
+        from igny8_core.business.billing.services.limit_service import LimitService, HardLimitExceededError
+        try:
+            LimitService.check_hard_limit(account, 'sites', additional_count=1)
+        except HardLimitExceededError as e:
+            from rest_framework.exceptions import PermissionDenied
+            raise PermissionDenied(str(e))
+        
         # Multiple sites can be active simultaneously - no constraint
         site = serializer.save(account=account)